Electrical control system



Line 29, 1943. H. o. wlLsbu 2,323,266 I ELECTRICAL CONTROL SYSTEMOriginal Filed 06x. so, 1936 S oggci F11 31; :59 57 19 3nnentor flerberf0. Mi 15012 By g Gttorneg Patented June 29,1943

ELECTRICAL CONTROL SYSTEM Herbert 0. Wilson, Benton Township, ColumbiaCounty, Pa., assignor to Thomas A. Edison, Incorporated, West Orange, N.1., a corporation of New Jersey Original application October 30, 1936,Serial No. 108,420. Divided and this application March 26, 1940, SerialNo. 325,935

8 Claims.

This invention relates to electrical control systems, and moreparticularly to such a system employing a switch or relay which isthermally thrown and electromagnetically maintained in thrown condition.The present application is filed as a division of my co-pendingapplication Serial No. 108,420, filed October 30, 1936, which becamePatent No. 2,242,636 on May 20, 1941. The particular illustration of thepresent invention has been presented in connection with a switch orrelay of the so-called vacuum type (involving a sealed container, forthe contacts, which is evacuated of air and may optionally contain afilling of inert gas), though obviously as to many aspects of theinvention this feature of illustration is non-limitative.

It is an object of my invention to provide a generally improved controlor switch system of the class first above described, and to provideimprovements in such a system.

It is another object of my invention to provide an improved switch orrelay, which throws after a predetermined delay, and which will quicklybe conditioned for repeated throwing with a similar delay.

' Other and allied objects will more fully appear from the followingdescription and the appended claims.

.In the description reference is had to the accompanying drawing, ofwhich Figure 1 is a view, generally cross-sectional,

though elevational as to components within the envelope and diagrammaticas to certain circuit elements, of a control system embodying myinvention, and

Figure 2 is a partial cross-sectional .view taken along the line 2-2 ofFigure 1.

In the drawing I have illustrated a switch or relay with a thermalelement to provide a predetermined time interval between the inceptionof .current supply to the switch and the throwing of the switch, andwith electromagnetic means for maintaining the switch thrown during thecontinuance of current supplythis maintenance by the electromagneticmeans permitting the cooling of the thermal element to recondition thedevice for proper quickly repeated operation should that be desired. Ingeneral in the following description, I shall first consider thearmature and core system, secondly the balance of the magneticstructure, and finally the general organization of the relay and of thesystem in which it is employed.

In the figures there will be seen the elongated evacuated envelope I,provided at one of its extremities with the seal 2, through which sealpass a plurality of lead-in wires, shown as three wires 3, 4 and 5,hereinafter referred to. Longitudinally within the envelope, for examplenear one side thereof in manner hereinafter more detailedly described,is supported a magnetic core systemcomprising two pole members 2' and H2of magnetic material such as iron, and for example of rectangularcross-section (transversely of the envelope) The pole members areserially arranged and longitudinally spaced apart to form a small gap 2l3 between their mutually exposed respectiv ends or faces HI and 222; itis convenient to hold them in the specified relationship by a flat,non-magnetic plate 2 secured to the bottom of each. Near'the gap 213 andtoward the center of the envelope therefrom I provide a flexiblysupported armature iii of magnetic material; this may be relativelyshort (1. e., longitudinally of the envelope), and of a rectangularcross-section (i. e., transversely of the envelope) of the order of thatof the pole members. The flexible support of the armature is one whichpermits movement toward and away from the gap transversely of theenvelope, and is desirably a resilient one; it may be provided bysecuring the armature to the core-system side of a light leaf spring ll,preferably of non-magnetic material such as phosphor bronze or berylliumcopper.

The spring I1 is conveniently extended toward the seal 2 to be clampedin the usual stack or washer assembly III, which may be secured to thepole member 2! I. The armature is biased away from the gap, as by asuitable tensioning of spring l1; but it is limitedly biased, in thatits movement away from the gap is restricted (by means hereinafterapparent) to the originally mentioned nearby position. A system ofcontacts is associated with the armature in suitable manner, such asthat hereinafter set forth, to be influenced by its movement.

It will be understood that upon magnetic excitation of the core systeme.g., serial excitation of the two pole members 2 and 2l2-the armature 2l6will be-attracted to movement toward the gap to effectively shorten thelatter, or reduce its reluctance. In the illustrated arrangement thearmature has been arranged for mOvement into juxtaposition with portions(2 and 242) of the top sides of both pole members. Thus these polemembers may be formed with the respective oflsets 2Il and 252 toward thearmature, and theportions 2" and 242 may lie between therespective'oflsets and the gap,-the

armature being centralized over the gap but extending to some extentover these portions.

For producing the serial magnetic excitation of the core system a coil34 may be provided around the envelope I, so that the coil axis isparallel with and near to the pole members 2l|2i2; and it will beunderstood that upon electrical excitation of the coil (as by impressionof 'a suitable voltage across the coil leads 34a and 34b and consequentcurrent flow through the coil) the pole members will be serially excitedin the required manner. To heighten the efficiency of the excitation,however, and at the same time to provide excellent mechanical supportand centralization of the elements within the envelope, the magneticsystem may include certain further elements. These will be brieflydescribed in the interest of completeness of description of a preferredembodiment; it will be understood, hwever, that they are not inthemselves claimed herein, being both disclosed and claimed in myco-pending application above referred to.

The further elements of the magnetic system within the envelope maycomprise two spring rings l9 and of magnetic material such as steel,each for example in the form of a leaf spring bent into the shape of theletter C (i. e., an almost closed circle), excepting preferably for asmall central flattened portion l9a or 20a. Each of these rings I3 and20 fits snugly and preferably presses against the interior wall of theenvelope l (excepting in its flattened portion Ha or 20a).Longitudinally they are positioned on opposite sides of the gap 2l3; theinterior surface of the flattened portion I911 of i9 is secured againstthe bottom or outer surface of pole member 2| l, and the interiorsurface of the flattened portion 20a of ring 20 is secured against thebottom or outer surface of pole member l2. The rings may thus form asignificant mechanical support and centralizing means for the polemembers or core assembly (to which in turn other elements are supportedthrough the insulating stack l0) at the same time they approach closelyto the inside of coil 34 at separated longitudinal positions--forexample either side of the center, and intermediate the coilextremities-and thus form eflicient means for collecting the magneticfield of the coil and passing it through the portion of the core systemwhich includes the gap H3.

The further elements of the magnetic system outside the envelope, theuse of which is a further contribution to the effectiveness of themagnetic system, may include magnetic cylinders '39 and 40 extendinginternally of the coil 34 from the respective coil extremities tooverlap the respective rings is and 20. These cylinders desirably fit asclosely as practicable over the envelope I; in turn they preferably fitas closely as practicable within the coil 3|; they are of course of suchlength that an appreciable gap is left between them. This gap being ofrelatively higher reluctance, the field collected by the cylindersnaturally follows the much lower-reluctance circuit from either cylinderthrough the envelope to the respective collecting ring [9 or 20, throughthe core system across the gap 2| 3, and from the other collecting ringthrough the envelope to the other cylinder. Finally still higherefficiency may be obtained by extending the outer extremities of thecylinders 39 and 40 around the coil ends, as by the illustrated cylinderflanges 39a and 40a of magnetic material, and joining them magneticallyas by the external cylinder 31 of terest of simplicity in the drawingthe coil 33 is only fractionally shown, but that it is intended forexample to fill the space bounded by ttention may now be given to thegeneral organization of the switch or relay of Figures 1 and 2. Thespring 11 will be seen to be extended away from the stack ID for aconsiderable dis-' tance beyond the armature, and to have secured to itsbottom surface near its extremity a contact 30. .Below this contact 3|)is provided a fixed contact 3l-for example secured to the top of thepole member 2l2. The contacts 30 and 3| are normally in slight spacedrelationship, forming the normally open switch A. On the top of spring11 nearer the stack ill-for example above the armature 2l6-is secured acontact 32; a cooperating contact 33 is provided thereabove to form aswitch B. The contact 33 is shown carrled on the bottom of a bimetallicarm 9 near one extremity thereof, .the arm being clamped at its otherextremity in the insulating stack II. The bimetallic arm 9 is surroundedby a heater winding 9a, of which one extremity is electrically connectedwith contact 33 (as by connection to the arm 8) and of which the otherextremity is connected to 8. lug 9b clamped in the stack II. Thebimetallic arm 8 and contact 33 form the limiting means for upwardmovement of the upwardly tensioned spring ll, so that switch B isnormally closed. When the arm 9 temperature is at or near ambient thedescribed normal positions, as illustrated, will be occupied by thevarious components. When the arm 9 is heated, however, as by passage ofcurrent through the heater winding 9a, the arm moves downwardly,maintaining switch B closed and forcing spring I! downwardly to closeswitch A.

Contact 31 is connected with lead-in wire 3, for example through polemember 212, plate 2, pole member 2| l, and a lug Ila. clamped againstthe pole member 2 and welded to the lead-in wire. With lead-in wire I isconnected springs i1, and hence contacts 32 and 30. With leadin wire 5is connected the lug 9b, and hence. through the heater winding 9a, thecontact 33. Thus between lead-in wires 3 and 3 lies electrically theswitch A, while between the leadin wires 4 and 5 lie electrically theserially arranged heater winding and switch B. In Figure 1 there hasbeen schematically indicated as I a current source. .One terminal 8a. ofthe source is connected with the lead-in wire 5 and with a lead 340, tocoil 34. The other terminal 817 of the source is connected throughacontrol switch 1 with lead-in wire 3, while lead-inwire 3 is connectedto the other coil lead 34b. Thus the heater winding is connected acorssthe source through the switches I and B, while the coil 33 is connectedacross the source through the switches I and A.

When the control switch 1 is closed the heater winding 9a is energized,since switch B is normally closed; this energization heats the arm 3 andthe latter moves downwardly. After a predetermined time interval switchA will be closed,

the armature 2H5 by that time having been asaaaoo said device andmaintaining said switch in said moved toward but not yet fully into theposition it occupies when the magnetic system is energized. But upon theclosing of switch A, switch I of course still being closed, the coil 34and hence the magneticrsystem are energized, attracting the armature M6to move an additional distance, and thus flexing the intermediateportion of spring l'l downwardly and opening switch B. This opening ofswitch 3 breaks the current flow through the heater winding, so that thearm forthwith begins the process of cooling and restoration to itsinitial position; but the spring I1 is maintained downwardly, and switchA closed, by the excitation of coil 34, which continues until thecontrol switch I is opened.

The completed downward movement of any portion of the spring ll-whichafter closing of switch I is thermally delayed and electromagneticallymaintainedmay be utilized-for any desired purpose and in any desiredmanner. By way of simple illustration I have shown a load 8 intended toreceive current only during intervals of downward spring position, andhave indicated the simple connection of the load in parallel with thecoil 34.

The switch system so organized presents, over various combinations ofdevices directed to a generally similar purpose, the distinct advantageof extreme simplicity. Broadly this results,

among other things, from the electromagnetic means operating directly onthe thermally responsive switch A itself, to take over the control ofthat switch from the thermal element; or, in a slightly differentview,'from the community of structure andof response to the coil of boththe switches A and B.

It will be understood that in respect of the thermal device which closesthe switch A there is no necessary limitation to a bimetallic strip suchas 9, as obviously other thermal devices may be employed. It is also tobe understood that while the device has been shown as an electro-thermalone-i. e., heated by an electric current-this is not essential forcertain purposes. Thus the heating winding 90. and connections theretomay be omitted, or equivalently the switch I (shown in series withlead-in wire 5 in Figure 6) opened:

the system will then function, assuming switch I closed, to close switchA and keep it closed when and after the thermal element (e. g.,bimetallic arm 9) has been heated to a predetermined temperature by anymeans, such as ambient temperature.

While I have illustrated and described my invention in terms of aparticular embodiment thereof, it is to be understood that I intend nounnecessary limitations by virtue of the details of that embodiment,which may, obviously be varied within wide limits without departure fromthe spirit of my invention, or from its scope as expressed in thefollowing claims.

I claim:

1. In a control system to which operating current may be supplied andwhich includes an electro-thermal device normally energized, formovement thereof, upon the supply of said operating current: thecombination of a switch normally mechanically responsive to said devicefor throwing from first to second conditions and vice versa upon saidmovement and the opposite movement, respectively, of said device; andmeans, electrically connected with said switch and rendered effectivethereby upon a throwing thereof to said second condition in response tosaid supply of second condition throughout the contin anc of said supplyof currents.

2. In a contmlsystem to which operating current may be supplied andwhich includes an electro-thermal device normaliy'energized, formovement thereof, upon the supply of said operating current: thecombination of a movable member normally positioned for mechanicalresponse to said device, whereby said member is normally moved inrespective directions upon said movement and the opposite, movement ofsaid device; means, electrically actuated by said member upon a movementthereof in response to said supply of current, for moving said memberout of position for response to said device and maintaining the same outof such position throughout the continuance of said supply of current;and means, responsive to the movement of said member out of suchposition, for discontinuing the energization of said device throughoutsaid continuance of current supply.

3. The combination according to claim 2, further including switch meansmechanically thrown by the movement of said member out of therecitedposition. a

4. In a control system to which operating current may be supplied andwhich includes an electro-thermal device normally energized, formovementthereof, upon the supply of said operating current: thecombination of a movable member normally mechanically responsive to saiddevice for movement in first and second directions upon said movementand the opposite movement, 'respectively, of said device; and means,electrically actuated by said member upon a movement thereof in saidfirst direction in response to said supply of current, for discontinuingthe energization of said device and retaining said member againstmovement in said second direction throughout the continuance of saidsupply of currents.

5. In a control system to which operating current may be supplied andwhich includes an electro-thermal device normally energized, formovement thereof, upon the supply of said operating current: thecombination of a movable member normally mechanically responsive to saiddevice for movement in first and second directions upon said movementand the opposite movement, re spectively, of said device; means,electrically actuated by said member upon a movement thereof in saidfirst direction in response to said supply of current, for effecting afurther movement of said member in said first direction and renderingsaid member unresponsive to said device throughout the continuance ofsaid supply of current; and means, responsive to said further movement,for discontinuing the energization of said device throughout saidcontinuance of current supply.

6. The combination according to claim 5, fur.- ther including switchmeans mechanically thrown by said further movement of said member.

'7. In a control system to which operating current may be supplied andwhich includes an electro-thermal device normally energized, formovement thereof, upon the supply of said operating current: thecombination of a switch normally mechanically responsive to said devicefor closing and opening upon said movement and the current, fordiscontinuing the energization of opposite movement, respectively, ofsaid device; and eiectromasnetic means, magneticall influencing saidswitch and electrically connected in series therewith for actuation uponclosure thereoi, or discontinuing the energization of said device andmaintaining said switch closed throughout the continuance of said supply01' currents.

8. In a thermally thrown, electromagnetically maintained switch system:the combination of a bimetallic arm and a cooperating switch arm carryinrespective contacts, said switch arm being biased in the direction ofsaid bimetallic arm (or closure of said contacts, and said bimetallic ambeing heatable for movement of itself and said switch arm in theopposite direction while maintaining said contacts closed; a. heaterwound on said bimetallic arm and connected in series with said contactsfor energization therethrough; and means, including a switch operated bysaid switch arm upon a. predetermined movement or said bimetallic andswitch arms in response to said energization of said heater, for furthermoving said switch arm to place and maintain said contacts in an opencondition and said 10 heater in a de-energized condition.

HERBERT 0. WILSON.

